Australian Monthly Climate Summary: July 2006

Tuesday 2 August, 2006

In Brief

For the third successive month, the far west of the country was very
dry, accompanied by much warmer than average maxima and cooler than
average minima. Apart from some parts of the far east, remaining parts
of the continent tended to be wetter than normal, with below average
daytime maxima.

Details

Temperatures:

Averaged over the country as a whole, mean July maximum and minimum
temperatures were both marginally below the median. Maximum
temperatures were more than 1°C above average in a band running from
southeast Queensland to northeast Victoria, and also in the west of WA.
Values were in the top decile across southeast Queensland, inland
southern to central NSW, northern Victoria and parts of the west coast
of WA.

Maximum temperatures were below the 1961−90 normal over most of both the
NT and SA, as well as eastern and northern WA, far north Queensland and
far western NSW. A few patches, mainly in the tropics, had anomalies
below −1°C, with isolated spots below −2°C. Most of Cape York Peninsula
had maximum temperatures in decile 1.

The pattern of minimum temperature anomalies was somewhat different:
conditions were mostly cooler than normal west of a line joining the
coastal SA/WA border with the coastal NT/Qld border, with generally
positive anomalies to the east. Large areas of the north and west more
than 1°C cooler than average, with much of northern WA and the north of
the NT having minima within the coolest one-tenth of the post−1950
record. A few small patches had record low mean minima.

In contrast, minimum temperatures were more than 1°C higher than the
long-term average in a region covering the southern half of Queensland,
parts of the southern NT and some of western SA. Similar anomalies
occurred in the far southeast of the mainland and the far north of
Tasmania. A large area in southeast to central Queensland had anomalies
over +2°C, but decile 10 values were mainly confined to a few small
patches in the southeast.

For the third successive month, a significant fraction of western and/or
southern WA had rainfall within the driest one-tenth of the historical
record dating from 1900. The area-average for southwest WA was 32% below
normal. For the May to July period in southwest WA, the area-average
rainfall of 139 mm (−55%) was the driest on record by a very large
margin. The second and third driest were 191 mm in 1976 and 206 mm in
1940.

Rainfall in July was also below average over parts of southern SA,
in patches of western, southern and northeast Victoria, as well as in
parts of Tasmania.

However, across Australia as a whole, July was wetter than normal (+6%)
with a rank of 72 out of 107. Totals in decile ranges 8−10 covered most
of the NT (+30%), eastern WA, the northern two-thirds of SA (+44%), the
western two-thirds of Queensland (+37%) and a large part of western NSW
(+18%). Spots of highest on record were observed in eastern WA, the west
coast of SA and in Queensland just south of the Gulf of Carpentaria.